« ForrigeFortsæt »
ofits powers as old age advances. Effects of healthful stii muli on the syitem. Property of gastric juice in diffolving dead Heth, while it lotes its power upon living tleh. Exemplified by the curious facts, first noticed by Mr. John Hunter, of the stomach itself after death, being corroded by: the gastric liquor. Hunger probably proceeds from the ftinulus of the gastric menitruum on the nerves of the stomach.
Powers of the living principle preserved and improved by moderate exercise ; diminished and exhausted by too violent exertions.--Restored by food and rest. Habit increases in a wonderful manner the active power of parti: cular nerves, exemplified in dancing, playing upon musical inftruments, &c. Great strength of body usually attended with a diminution of the mental powers, and vice versa; hence the debilitated body, and diseases incident to studious and sedentary persons. Great and sudden effects of the passions on the living principle.
Powers of the living principle uniformly and uninterrupt edly conveyed to every part of the body. All the muscular fyftem replete with it, and fo tenacious of it, that it remains for fome time after the death of the animal. This time different in different animals. In man and quadrupeds, whose organs of respiration are of the same kind, a Thort time. In frogs, vipers, eels, turtles, and other amphibia, for a longer period, and inay be renewed by stimulus, as appears from various experiments.
We shall conclude mentioning our Author's obfervations on the living principle, by transcribing part of the thirtyfixth paragraph, because it gives an ingenious solution of some phænomena in the animal oeconomy, and in a manner which we do not recollect to have met with before.
• It not unfrequentiy happens, during the latt efforts of nature for the continuance of life, that flight convulsive motions of the muscles, particularly of the eyes and face, precede death. This effect probably arises from their vicinity to tặe principal seat of the living powers. But the more reinote inuscles are not affected; for from the want of a fufficiency of life, they are incapable of being acted upon. In such cases, after death, the muscles are found to be in a relaxed ftate, being soft and flexible," &c.
From this analysis of what Dr. Gardiner fays of the liv. ing principle, it is evident, that the medical reader will find much entertainment from this part of the performance at large. But in what light the metaphysician or the divine will consider what is here faid of the living principle, is what we cannot take upon us to determine. naturally be asked ; Is there a principle of life in the body diftinct from the inmaterial principle? This is a point we do not mean to enter into a difcuffion of. All we shall ob
ferve is, that the several phænomena ascribed to the living principle, do not appear to us in the least inconsistent with the idea of its being immaterial. The renovation of mus çular action in some animals after death ; is not a renewal of the living principle; but merely a renewal of a mechanical action, the effect of which exists for a longer time in some animals than in others, even after the primary cause of it is removed.
The second section treats of the nerves, of sympathy, and of ftimuli.
Sympathy existing between all parts of the body, arises probably from the unity of substance between the nerves and the brain. Anomalous sympathies not satisfactorily accounted for from the anastomoses, or connections of the nerves with each other-owing to morbid irritability. The stomach, the principal feat of the most reniarkable sympa, thetic affe&tions which happen in valetudinary states of the body.
Healthy ftimuli are such as by their action support the ļiving principle. Noxious stimuli, such as destroy or lessen it.—The most powerful and falutary remedies most likely to become noxious stimuli. Stimuli lose their powers on cer. tain persons by habit. Some stimuli ac imperceptibly on the body, and yet occasion the most considerable changes in the system, either in producing diseases, ar restoring health. Instances-putrid marsh-miasmata -effect of Peruvian bark neceffity of some ftimuli producing their effects without consciousness-nerves of the skin from their number and sensibility most likely to be affected by the viciffitudes of heat and cold.
The nerves of the stomach, and bowels subject to a greater variety of imperceptible ftimuli, than those of any other part of the body. The effects of morbid stimuli conveyed to distant parts with the same unconsciousness of the ftomach being affected—In delicate conftitutions certain stimuli are capable of producing a suspenfion of the animal actions. Thus fainting from slight causes-whole system affected from Night and even agreeable ftimuli applied to the olfactory nerves, in irritable female habits. A blow on the pit of the stomach may induce a fufpenfion of the vital powers, and even death itself, though upon examination after death, that viscus shall not appear to have suffered in its texture-Infenfibility, and often death, from a blow on the head, without any apparent injury done to the skull or brain-Every sudden and unexpected pain more dangerous than that which is gradually brought on-instance the great degree of pain the human body is often capable of bearing be
fore dissolution, in many cruel modes used in some countries of putting malefactors to death. Affections of the mind influence the body, and vice versa--thus in chronic diseases, attended with præternatural irritability of the nerves; the paroxyfm suspended for a time, while the mind has been under the influence of some particular passion or yiolent emotion :-hence the necessity and great use of keep ing the mind constantly employed either by business or amusement in the cure of certain diseases. Effects of opium and of poisons communicated by sympathy. In habits where the admiffion of opium into the stomach, in whatever dose or form it may be given, affects the patient disagreeably, it Thould be injected into the rectum by glyfter-nerves of the rectum bear opium in larger quantities than those of the stomach. Deadly effects of the lauro-cerasus; though its leaves boiled in milk may be taken with impunity, yet from the possibility of its producing accidents in children and delicate conftitutions, ought to be banished from every species of cookery. The mode in which the vegetable poisons operate not to be learnt by the inspection of the body. The observations on this point are fo judicious, and so necessary to be known by all practitioners, particularly with respect to juridical information ; that we cannot better close this acçcount, which this accurate writer gives of the effects of sympathy, than by giving the whole of it to our readers.
• When undoubted information is received that the deceased had taken a deleterious fimple, or compofition, in such quantity as is known to prove a poison to the human body; that, immediately afterit was swallowed, such symptoms arose as are usually the consequence of the poison exhibited; that these symptoms increased in violence, and continued till they produced death ; on such occa: fions there can be little doubt as to the cause; and if part of the poison is (be) found in the stomach and bowels, the evidence amounts to a demonstration. But without these circumstances, in our judicial declarations, we can prove nothing from any. ap rance of the body on diffection : for the fuffusion of blood lometimes observed in different parts of the body, particularly about the face, neck, and breast, from the small vessels of the skin, is no more than what happens in almost every case of sudden death, and even takes place sometimes on a stop being put to the circulation, on the demise of people after chronic diseases. Neither do those flight degrees of redness, from the blood ftagnating in the small vessels of certain parts of tbe stomach and bowels, after death, prove that any thing is unnatural, or characteristic of particular poisons. All must be referred to the particular operation of the poison on the nerves of the stomach, by which their power of conducting the principle of life is destroyed. Its effects are by geperal sympathy, quickly communicated to the rest of the system,
and produce a suspension of all action, but without making the smalleft apparent alteration on the structure of the nerves or other parts.'
In the third section Dr, Gardiner proceeds to consider the effects of heat and cold.
The writer first takes a review of Dr. Crawford's ingenious theory upon this subject; and although he agrees with him in his general principles, yet he differs with him in his inode of realoning, and argues against the manner in which the Doctor supposes the animal heat to be fupported.--He admits the double exchange of the principles of heat and phlogiston in the lungs, bụt cannot conceive how this Thould become the source of animal heat in the circulation ; a circumstance accounted for by Dr. Crawford; by observing that the blood in the course of the circulation abforbs a great quantity of phlogiston, and is thereby obliged to part with a portion of its heat. Dr. Gardiner fupposes, on the other hand, that part of the fire extricated from the air ini the lungs is expended in converting the moisture accompanying respiration into vapour, and that the rest is absorbed by the blood, which in circulation, gradually undergoes such a change from the state it possessed in the large arteries, as lefsens its capacity for containing absolute heat, and of course there will be a gradual extrication of part of that fire it held.
The author likewise differs from Dr. Crawford with regard to the mode in which that power in animals is produced, by which they are enabled to maintain nearly the same temperature in different degrees of heat; which the latter thinks is owing to the degree of heat in which the animal is placed, diminishing proportionally the attraction of the blood for phlogiston.
The writer alledges, that from the commencement of animal life there is a conftant generation, and a constant consumption of heat ; this takes place after birth :-Deficiency in the organs of the fætus for generating heat, fupplied for a time by the mother. Generation of heat commences with respiration, illustrated by the process of incubation, admirably well detailed here. Review of the experiments recorded in the Philofophical Transactions, concerning the degree of heat the human body was able to bear without any sensible inconvenience, and which induced an opinion, that the living body possessed a power of resisting for a time any addition or diminution of heat above or be. low the healthy standard. The author contends, that the living body poffefses no such power of resisting or destroying heat, when placed in an air heated greatly above its own temperature. This circumstance Dr. Gardiner accounts 0.
for in a more simple and satisfactory manner; observing that this balance of heat and cold, and the prevention of any remarkable change in our temperature, is accomplished by various actions being by turns excited in the body for the production of heat or cold, and for that degree of either which best corresponds with the exact regulation of the standard heat. In temperate air, these operations carried on with such case, that no fatigue is experienced from their continued action. In air extremely hot or cold they act with a degree of violence on the body, and the system is ex, cited to such actions as correspond with the nature of the stimulus. Exemplified by a review of the effects of heat applied to the body as stated in these experiments.
Pulse quickened, and perspiration increased-heat produced and increased by acceleration of circulation ; this if suffered to accumulate would destroy the animal-hence the neceffity of a sweat being produced, which contributes grcatly to carry off the surplus of heat. Loose spungy texture of human body makes the admission of heat into it gradual and flow; its bulk too, fuppofing it a mass of inanimate matter, would require a considerable time to be heated thoroughly to a few degrees above its temperature. As animated, na ture is employed in counteracting the effects of the heat by the refrigerating process of sweating, and the consequent expenditure of heat in the formation of vapour. Powerful effects of evaporation, exemplified by the practice of cooling wine in hot countries, by wrapping up the bottles in wet cloths, and hanging them up in the sun, and by other cur rious facts.
The powers of life proportionally exhausted by an accumulation of heat above the natural standard, -Bodies in which heat is accumulated resist for a time the effects of cold air; hence the gentlemen who were so overheated in the experiments, felt no inconvenience from exposure to cold air. But they experienced more or less of debility and languor, trembling of the hands, and other symptoms, all shewing, that while they remained in this heat, there was an uncommon exertion of the powers of life in obviating the effects of it, and that by a continuance of the fame process these powers may be totally exhausted. Cautions against cooling the body too suddenly after being overheated.
Power of living bodies to refift cold as well as heat. Animals possess a power, according to Mr. John Hunter, of generating heat' for this purpose. Principle of life begins to decline when an animal body, or part of it is cooled considerably below its standard heat, and continues declining till totally extinguished recovered by gradual admission